Valujevs, Valujeva and Vankova were also convicted of arranging sham marriages.

However, a fifth defendant, Laimonas Belka, 52, of Sutton Road, Leverington, was cleared by the jury.

The case was brought out of the ongoing Operation Endeavour investigation between Cambridgeshire Police and the Gangmasters’ Licensing Authority into the explotation of migrant workers in the Fenland area.

Police say the four controlled bank accounts held by the victims and placed them in debt bondage by withholding work and overcharging for rent and transport.

Valujevs, Valujeva and Vankova also offered or forced three women to take part in sham marriages in order to pay debts.

One woman refused to go through with a marriage, despite being offered £2,000, while another said she was not paid for marrying a man in India, despite being offered £1,500 to do so.

Valujevs and Mezals were previously convicted of acting as unlicensed gangmasters following a trial at Blackfriars Crown Court in 2014. However, that jury failed to reach a verdict on the sham marriage charge.

Detective Inspector Jenny Bristow, of Cambridgeshire Police, said: “I hope this court case and the previous one have shown how seriously we and the courts take this type of exploitation.

“The operation run by the defendants left many people in abject poverty and debt and all four defendants ruthlessly took advantage of the victims for their own gain.

“We know the exploitation of vulnerable people, many of whom simply want to make a better life for themselves in the United Kingdom, is still happening.

“However, we are committed to working with colleagues in partner agencies to protect vulnerable people and bring those who commit criminal offences against them to justice.”